The present invention relates to a method and an apparatus for processing a semiconductor, and in particular, to a method and an apparatus for successively processing a semiconductor.
Semiconductor devices are produced in fine dimensions these days, and hence higher dimensional precision is required in the machining of the semiconductor devices. A semiconductor processing apparatus conducts physico-chemical machining on a semiconductor wafer using heat and/or plasma. In such a processing apparatus, a product resultant from chemical reaction in the apparatus piles as a residual product on an inner wall of the apparatus. The residual product increases with a lapse of time, and a state to process wafers gradually changes as a result.
That is, while the operation to process the wafer is repeatedly executed, the state of machining the semiconductor device changes and performance of the semiconductor device is resultantly deteriorated.
To solve the-problem, the product piled on the inner wall of a processing chamber is cleaned ordinarily using plasma. However, the plasma cleaning cannot completely remove the product piled on the inner wall of the processing chamber. Therefore, as described above, while the operation to process the wafer is repeatedly executed, thickness of a layer of the product piled on a part of the inner wall of the chamber gradually increases and hence a contour of machining the semiconductor device gradually changes. Therefore, before the change in the machining contour becomes a problem, constituent components or parts of the semiconductor processing apparatus are replaced or cleaned in ordinary cases.
In addition to the pile of the product, variations in various states of the processing apparatus also contribute to the variation in the machining contour of the wafer. To cope with this problem, attempts have been conducted. For example, a plasma processing apparatus senses a change in an internal state thereof and feeds a result of the sensing operation to a process condition of the plasma processing apparatus to keep a process characteristic at a fixed level.
For example, JP-A-6-132251 (article 1) describes an etch processing apparatus or an etching apparatus which monitors a result of etching for each wafer to determine whether or not the monitored result satisfies an inspection condition. If the result does not satisfy the condition, the etching apparatus modifies the process condition to restore the process characteristic.
JP-A-10-125660 (article 2) describes a plasma processing apparatus which measures an electric signal reflecting a state of plasma while processing a sample. According to a value of the signal thus measured, the apparatus calculates a predicted value of a plasma process characteristic and diagnoses the plasma state according to the predicted value.
JP-A-2001-267232 (article 3) describes a method in which monitored data of results of wafer process and process states in the past are stored in a database. According to monitored data of the wafer, a result of process of a wafer at present is predicted to conduct optimization control for the process.